Apparatus for sensing a dimension of sheets of material to be transported through an electrostatic reproduction machine

ABSTRACT

Apparatus for regulating the removal of heat from a fusing assembly in accordance with a dimension of the sheets of material transported thereto is disclosed in accordance with the teachings of the present invention. Heat transfer means is energized by switch means, the latter being adapted to be contacted by activating means. The switch means and activating means are disposed for relative movement therebetween such that a contacting relationship is established when the dimension of the sheets of material included in a supply therefor exceeds a predetermined dimension. Movement between the switch means and activating means is effected by the adjustment of sheet guide means, said adjustment enabling said sheet guide means to receive sheets of material.

United States Patent Sisson et al.

[ APPARATUS FOR SENSING A DIMENSION OF SHEETS OF MATERIAL TO BE TRANSPORTED THROUGH AN ELECTROSTATIC REPRODUCTION MACHINE [75 Inventors: Jeffrey L. Sisson, Rochester; Paul D.

' Norder, Fairport, both of NY.

[73] Assignee: Xerox Corporation, Stamford,

UNITED STATES PATENTS 2,692,118 10/1954 Hollaway 165/134 June 28, 1974 Primary Examiner-Charles Sukalo 5 7] ABSTRACT Apparatus for regulating the removal of heat from a fusing assembly in accordance with a dimension of the sheets of material transported thereto is disclosed in accordance with the teachings of the present invention. Heat transfer means is energized by switch means, the latter being adapted to be contacted by activating means. The switch means and activating means are disposed for relative movement therebetween such that a contacting relationship is established when the dimension of the sheets of material included in 'a supply therefor exceeds a predetermined dimension. Movement between the switch means and activating means is effected by the adjustment of sheet guide means, said adjustment enabling said sheet guide means to receive sheets of material.

5 Claims, 2 Drawing Figures PATENTEOaunza 1924 saw 2 or 2 APPARATUS FOR SENSING A DIMENSION OF SHEETS OF MATERIAL TO BE TRANSPORTED THROUGH AN ELECTROSTATIC REPRODUCTION MACHINE This invention relates to heat removal apparatus and, more particularly, to apparatus for regulating the removal of heat from a fusing assembly included in an electrostatic reproduction machine in accordance with a dimension of the sheets of material transported therethrough.

In the practice of xerography as described in US. Pat. No. 2,297,691 to Chester F. Carlson, a xerographic surface comprising a layer of photoconductive insulating material affixed to a conductive backing is used to support electrostatic images. In the usual method of carrying out the process, the xerographic plate is electrostatically charged uniformly over its surface and then exposed to a light pattern of the image being reproduced to selectively dissipate the charge in the areas where light strikes the layer. The undischarged areas of the layer thus form an electrostatic charge pattern in conformity with the configuration of the original light pattern. i

' The electrostatic latent image may then be developed by contacting it with a finely divided electrostatically attractabl'e material, such as a resinous powder. The powder is held in the image areas by the electrostatic fields on the layer; Where the field is greatest, the greatest amount of material is deposited; and where the field is least, little or no material is deposited. Thus, a viewable powder image is produced in conformity with the light image of the copy being reproduced. The powder is subsequently transferred to a sheet of paper or other support surface and suitably fused to thereby form a permanent print.

In US. Pat. No. 3,754,819 assigned to Xerox Corporation, the assignee of the present invention, the toner is fixed by passing the sheet of paper or other surface including the transferred image between a heated roller and a second roller in pressure contact therewith whereby the toner becomes fused to the sheet of paper. In accordancewith such techniques, the temperature to which the toner isgenerally raised is a temperature at which the toner particles coalesce or flow together and wet the paper surface to effect thereby a permanent bond.

The temperature to which the heated roller is maintained to heat conductively a given toner is dependent on the production rate, (i.e., copies per unit time) of a given electrostatic reproduction machine. Thus, for a machine having a low rate of production, such a temperature is significantly lower than a machine having a high rate of production. In the type of electrostatic reproduction machine described in the aforementioned copending application, the receiving medium on which is in contact with the rollers but not at the end portions of the pressure roller when the receiving medium admits of a dimension less than the maximum for which the fuser assembly is designed. Novel apparatus designed to prevent such effects on the pressure roller is disclosed in copending application Ser. No. 214,305 filed Dec. 20, 1971 and assigned to Xerox Corporation, the assignee of the present invention.

Briefly, the novel apparatus disclosed in the aforementioned application removes heat from selected portions of the fuser assembly by causing a heat transfer fluid to pass about the assembly during operation of the electrostatic reproduction machine. Although the removal of heat is preferred when paper admitting of a relatively short dimension is transported through the fuser assembly, it is necessary that the entire assembly be heated uniformly to obtain a proper fusing operation when paper admitting of a relatively long dimension is transported.

Therefore, it is an object of the present invention to regulate the operation of fuser assembly heat removal apparatus in accordance with a dimension of the sheets of material transported thereto.

It is another object of the present invention to provide apparatus located at the supply of sheets of material to detect when a dimension of said sheets exceeds a predetermined dimension to interrupt the operation of fuser assembly heat removal apparatus.

A further object of this invention is to provide apparatus that is operable in cooperation with the adjustment of sheet guide means to effect an interruption in the operation of fuser assembly heat removal apparatus when said sheet guide means is adjusted to receive sheets of material admitting of a dimension that exceeds a predetermined dimension.

Various other objects and advantages of the invention will become clear from the following detailed description of an exemplary embodiment thereof, and the novel features will be particularly pointed out in connection with the appended claims.

In accordance with this invention, there is disclosed apparatus for regulating the removal of heat from a fusing assembly in accordance with a dimension of the sheets of material transported thereto, including switch means located at the supply of said sheets of material and adapted to be activated for energizing heat transfer apparatus; and activating means adapted to contact the the developed electrostatic image has been transferred,

such as paper, is passed through the fusing zone longitudinally to the axis of the fuser roller (i.e., side ways as compared to lengthwise). The temperature to which the heater or fuser roller is raised in such a machine is sufficiently high because of the high rate of production, such that any portion of the pressure roller, which has a thick outer layer of resilient material, that is in continuous contact with the heated fuser roller may be deleteriously effected. That is, sufficient heat removal is provided in those areas wherein the receiving medium switch means when the dimension of said sheets exceeds a predetermined dimension, thereby interrupting the operation of the heat transfer apparatus. The switch means and activating means are disposed for relative movement therebetween, said relative movement being provided in response to an adjustment of movable sheet guide means whereby the latter is prepared to receive a differently dimensioned supply of sheets of material.

The invention will be more clearly understood by reference to the following detailed description of an exemplary embodiment thereof in conjunction with the accompanying drawings in which:

FIG. I is a schematic sectional view of an electrostatic reproduction machine embodying the principles of the invention; and

FIG. 2 is a schematic sectional view of the regulating apparatus in accordance with the present invention as utilized by the electrostatic reproduction machine.

For a general understanding of the illustrated copier/reproduction machine in which the invention may be incorporated, reference is had to FIG. 1 in which the various system components for the machine are schematically illustrated. As in all electrostatic systems, such as a xerographic machine of the type illustrated, a light image of a document to be reproduced is projected onto the sensitized surface of a xerographic plate to form an electrostatic latent image thereon. Thereafter, the latent image is developed with an oppositely charged developing material to form a xerographic powder image, corresponding to the latent image on the plate surface. The powder image is then electrostatically transferred to a support surface and fixed by a fusing device to cause the powder image to adhere permanently to the support surface.

In the illustrated machine, a document D to be copied is placed upon a transparent support platen P fixedly arranged in an illumination assembly, generally indicated by the reference numeral 10, positioned at the left end of the machine. Light rays from an illumination system are flashed upon the document to produce image rays corresponding to the informational areas. The image rays are projected by means of an optical system onto the photosensitive surface of a xerographic plate in the form of a flexible photoconductive belt 12 arranged on a belt assembly, generally indicated by the reference numeral 14.

The belt 12 comprises a photoconductive layer of selenium which is the light receiving surface and imaging medium for the apparatus, on a conductive backing. The surface of the photoconductive belt is made photosensitive by a previous step of uniformly charging the same by means of a corona generating device or corotron 13.

The belt is joumaled for continuous movement upon three rollers 20, 21 and 23 positioned with their axes in parallel. The photoconductive belt assembly 14 is slidably mounted upon two support shafts 23 and 24 with the roller 22 rotatably supported on the shaft 23 which is secured to the frame of the apparatus and is rotatably driven by a suitable motor and drive assembly (not shown) in the direction of the arrow at a constant rate. During exposure of the belt 12, the portion exposed is that portion of the belt running between rollers and 21. During such movement of the belt 12, the reflected light image of such original document positioned on the platen is flashed on the surface of the belt to produce an electrostatic latent image thereon at exposure station A.

As the belt surface continues its movement, the electrostatic image passes through a developing station B in which there is positioned a developer assembly generally indicated by the reference numeral 15, and which provides development of the electrostatic image by means of multiple brushes 16 as the same moves through the development zone.

The developed electrostatic image is transported by the belt to a transfer station C whereat a sheet of copy paper is moved between a transfer roller and the belt at a speed in synchronism with the moving belt in order to accomplish transfer of the developed image solely by an electrical bias on the transfer roller. There is provided at this station a sheet transport mechanism generally indicated at 17 adapted to transport sheets of paper from a paper handling mechanism generally indicated by the reference numeral 18 to the developed image on the belt at the station C.

After the sheet is stripped from the belt 12, it is conveyed into a fuser assembly, generally indicated by the reference numeral 19, wherein the developed and transferred xerographic powder image on the sheet material is permanently affixed thereto. After fusing, the finished copy is discharged from the apparatus at a suitable point for collection externally of the apparatus.

Further details regarding the structure of the belt assembly l4 and its relationship with the machine and support therefor may be found in the copending application Ser. No. l02,3 l2 assigned to the assignee of the present invention.

As has been noted hereinabove, copending application Ser. No. 214,305 discloses novel apparatus for preventing deleterious effects on the pressure roller caused by prolonged heating thereof when in contact with the fuser roller. It is preferred to energize this heat removal apparatus when sheets of material conveyed into the fuser assembly admit of a dimension that is less than a predetermined dimension. However, when the dimension exceeds the predetermined dimension it is no longer necessary to remove heat from the pressure roller. In fact, the fuser assembly should be uniformly heated and the heat removal apparatus should be deenergized. This may be effected by interrupting the operation of the pumping device that forces the heat transfer fluid to flow through the heat removal apparatus or by interposing an obstruction to the flow of the fluid through its conduit. To facilitate a ready understanding of the present invention, it will be assumed, for the purpose of explanation, that the activation of the apparatus described herein serves to de-energize the heat removal apparatus in either of the alternative manners described.

Referring now to FIG. 2, there is illustrated a schematic sectional view of one embodiment of the regulating apparatus of the present invention comprising switch means 42 and activating means 401 disposed in the environment of a suitable supply of sheets of material for the electrostatic reproduction machine. It is recognized that the material upon which the electrostatic reproduction machine may operate may comprise any suitable support such as paper, glass, plastic or the like. It will be assumed, for the purpose of simplifying the present discussion, that the material comprises paper. The supply of paper for the electrostatic reproduction machine is adapted to be stored in an elevator assembly, partially illustrated herein. A more complete description of the operation of a typical elevator assembly and the control means therefore is set forth in US. Pat. No. 3,768,806 and assigned to the assignee of the present invention. I

The portion of the elevator assembly depicted in FIG. 2 includes platform 30 and sheet guide means 31 and 32. The platform provides a support for the paper stacked thereon and is adapted to be indexed upward by suitable means, not shown, to position the top-most sheets of paper in proper alignment to be fed to a sheet transport mechanism, not shown. The sheet guide means is comprised of respective vertical members 31 and 32 having portions 311 and 312 disposed in face to face relationship. The members are spaced apart by a distance equal to a given dimension of the paper stacked upon platform 30. More particularly, the space defined by portions 311 and 312 is substantially equal to the length of the paper stacked upon platform 30. It is readily apparent that members 31 and 32 provide for the proper alignment of the paper and, therefore, are positioned along the longitudinal axis of platform 30. The width of each member 31 and 32, although not critical per se, may be less than the width of platform 30, yet is sufficient to properly align and restrain the paper.

The electrostatic reproduction machine with which the present invention finds application is capable of operating upon paper admitting of a wide range of lengths. Accordingly, members 31 and 32 must be adjustable to receive such paper. Thus, for example, the members 31 and 32 must provide proper alignment for paper supported by platform and admitting of a length of 11 inches, 13 inches or 14 inches. Each of members 31 and 32 are, therefore, supported on a suitable support such as a rigid guide 33 having an aperture therein and mounted for slidable movement therein by bolt means 312 and 322, respectively. Moreover, members 31 and 32 are maintained in a proper vertical configuration by being slidably secured to lateral guides 35 and 34. The lateral guides are provided in a suitable wall or frame portion of the electrostatic reproduction machine. It is observed that member 31 is secured to lateral guide 35 by suitable fastening means 313. The fastening means may comprise a conventional machine bolt that passes through theaperture of lateral guide 35. Member 32 is similarly secured to lateral guide 34. Thus, members 31 and 32 are capable of being laterally displaced while preserving a proper vertical configuration. For further support, a rigid member, not shown, maybe bolted at one end thereof to bolt means 312 and at the other end thereof to'an extreme portion of drive means 41. Similarly, another rigid member, not shown may be bolted to bolt means 322 and to drive means 40, to be described.

The separation between members 31 and 32 may be manually'adjustedby an operator to enable the members to receive paper of various lengths. Member 32 is provided with an aperture 324 therein and through which passes a fixed indicator 36. The indicator is calibrated-in units of length and provides an indication of the length of. paper that may be stacked upon platform 30 and properly aligned by members 31 and 32. Thus,

anindication of the separation between members 31 and 32 is afforded.

Drive means is mechanically coupled to member 32 by suitable coupling means, such as the machine bolt 323, and is adapted to laterally displace the memberfLikewise, drive means 41 is mechanically coupled to member 31 by machine bolt 313 for laterally displacing that member. The drive means 40 and 41 are capable of being simultaneously moved in opposite directions to effect a change in the separation between members 32 and 31, respectively, while maintaining a symmetrical relationship with respect to a center line therebetween. Each of the drive means may, therefore, comprise a rack having teeth adapted to mesh with the teeth of pinion 38. It is appreciated that, if the drive means are oppositely disposed with respect to pinion 38, the clockwise rotation of the pinion causes the drive means to be laterally displaced in opposite directions to increase the separation between members 31 and 32. Conversely, the counterclockwise rotation of the pinion results in a decrease in the separation between members 31 and 32. Although adapted for rotation, the pinion is restrained from linear movement. Hence, the pinion may be secured to a wall or frame portion of the electrostatic reproduction machine by a journaled shaft. If desired, pinion 38 may be replaced by a conventional rubber roller adapted for frictional engagement with drive means 40 and 41.

Rotary motion is imparted to pinion 38 by knob 37 coupled thereto by endless belt 39. Rotation of the knob 37 by an operator causes endless belt 39 to rotate in the same direction, thereby imparting a rotary motion to pinion 38. Knob 37 and pinion 38 may, therefore, include conventional pulley means adapted to frictionally engage endless belt 39. Alternatively, belt 39 may comprise a wire or cable loop. Additionally, knob 37 and pinion 38 may each include a wheel having sprockets to engage an endless chain deployed thereabout. A more detailed description of the elevator assembly partially depicted herein is disclosed in copending application Ser. No. 270,577 filed on July 20,

1972, and assigned to the assignee of the present invention.

Switch means 42, briefly mentioned hereinabove, may comprise a conventional mechanical switching device, such as a microswitch or the like, having a pro truding member 423. The switch means may be fixedly secured to a wall or frame portion of the electrostatic reproduction machine by suitable fastening means, such as screws 42] and 422. The switch means 42 includes a pair of electrical conductors 424 adapted for electrical communication with the heat removal apparatus. As is understood by those of ordinary skill in the art, the contacting of the protruding member 423 by external means serves to activate switch means 42, thereby opening or closing the electrical contacts included thereon. Consequently, an electrical signal may be applied across the conductors 424 or removed therefrom in accordance with the opening and closing of the electrical contacts. Similarly, a conducting chantie] between the conductors may be established or interrupted in accordance with the opening and closing of the electrical contacts. Protruding member 423 may be spring biased and is interposed in the path of travel of activating means 401. It may be observed that the activating means comprises a rigid member supported by drive means 40. The rigid member may be displaced in a rightward direction until contact is made thereby with the protruding member 423. At the point of contact, the driving means 40 and 41 admit of a relative displacement whereby the separation defined by members 31 and 32 admits of a predetermined magnitude. A slight increase in such separation results in the activating of switch means 42.

The operation of the apparatus illustrated in FIG. 2 will now be described. It will be initially assumed that the paper to be stacked upon platform 30 admits of a length less than the aforementioned predetermined dimension/For the purpose of explanation, the paper may be, typically, 8 /2 X l 1 inch paper. Accordingly, an operator may rotate knob 37 which, in turn, rotates pinion 38. It is appreciated that rotary motion of the pinion drives the driving means 40 and 41 in opposite directions. Hence, the separation between members 31 and 32 is adjusted in a corresponding manner, an indication of the instantaneous separation being provided by the relative position of aperture 324 with respect to indicator 36. The direction of movement of members 31 and 32 is dependent upon the positions initially occupied thereby when knob 37 is rotated. The rotation of the knob is terminated when indicator 36 represents that the separation between members 31 and 32 is substantially equal to eleven inches. The illustrated elevator assembly is now adapted to receive 8 /2 X 11 inch paper and the members 31 and 32 provide a proper alignment therefor. FIG. 2 represents an 11 inch separation between members 31 and 32 and, as may be observed, activating means 401 does not exhibit a contacting relationship with respect to protruding member 423. Consequently, switch means 42 is not activated and the heat removal apparatus is not de-energized. Damaging effects to the end portions of the pressure roller are thus avoided.

Let it now be assumed that the 8 /2 X 11 inch paper is removed from platform 30 and that paper admitting of a length that exceeds the predetermined dimension is to be operated upon. Typically, 8 /2 X 13 inch paper may be stored on platform 30. Knob 37 is rotated in a clockwise direction to effect a clockwise rotation of pinion 38. Consequently, drive means 40 and 41 are displaced in opposite directions to increase the separation between members 31 and 32. It is appreciated that activating means 401 is movable with drive means 40 to approach protruding member 423. For the purpose of explanation, it may be assumed that activating means 401 contacts the protruding member when the separation between members 31 and 32 is slightly less than 13 inches, e.g., 12.75 inches. Thus, further rotation of knob 37 by an operator results in the activation of switch means 42. Consequently, when the separation defined by members 31 and 32 exceeds the predetermined dimension so as to receive sheets of material having a length in excess of said predetermined dimension, the activation of switch means 42 effects a deenergization of the heat removal apparatus. As has been explained hereinabove, it is contemplated that the heat removal apparatus may be de-energized by interrupting the operation of the heat transfer fluid pumping device or by interposing an obstruction to the flow of fluid through its conduit. Accordingly, conductors 424 of switch means 42 may be coupled to suitable control apparatus, not shown, which operates in response to the activation of the switch ,means to de-energize the heat removal apparatus. Such control apparatus is not a part per se of the present invention, nor is a description thereof necessary for an understanding of the instant invention. Alternatively, conductors 424 may be coupled to a conventional solenoid or other electromechanical device to effect the de-energization of the heat removal apparatus in response to activation of switch means 42.

lt may be appreciated that the rigid member includes an upper surface upon which the protruding member 423 may ride if drive means 40 is further displaced in the rightward direction. Hence, if an operator rotates knob 37 to increase the separation between members 31 and 32 such that longer paper, e.g., 14 inch paper, may be received thereby, the rigid member remains in contact with protruding member 423 and the activation of switch means 42 is maintained. A reversal in the direction of rotation of knob 37 results in a decrease in the separation between members 31 and 32 and the rigid member is displaced in a leftward direction. When 6 the rigid member no longer exhibits a contacting relationship with protruding member 423, the protruding member is returned to its illustrated position under the influence of the spring bias thereof. It is now readily apparent that the heat transfer apparatus is de-energized when paper admitting of a length that exceeds a predetermined dimension is stacked upon platform 30 and the heat transfer apparatus is energized when paper admitting of a length that is less than the predetermined dimension is stacked upon the platform.

Although the foregoing has been specifically described with respect to an elevator assembly which is utilized as a supply for sheets of material having various lengths, it is to be understood that the separation defined by members 31 and 32 may be adjusted to receive sheets in accordance with the width of such sheets. Thus, switch means 42 may be activated when the width of the supply of paper exceeds a predetermined dimension. Furthermore, the present invention should not be limited to the configuration wherein switch means 42 is fixedly secured and the activating means is supported by and movable with drive means 40. It is only necessary that the switch means and the activating means be disposed for relative movement therebetween. Accordingly, the switch means 42 may be supported by drive means 40 and the activating means 401 may be fixedly secured and adapted to contact the protruding member of the switch means. Moreover, the adjustment in the separation between members 31 and 32 such that the illustrated apparatus may accomodate differently dimensioned sheets of material may be attained by means other than the rotation of knob 37. Accordingly, either drive means 40 or 41 may be directly moved by operation of a lever affixed thereto. Alternatively, motive power may be applied to the drive means in response to the operation of a conventional electric motor. Similarly, one of members 31 and 32 may remain stationary and the other adapted to be moved with respect thereto.

While the invention has been particularly shown and described with reference to a specific embodiment thereof, it will be obvious to those of ordinary skill in the art that the foregoing and various other changes and modifications in form and details may be made without departing from the spirit and scope of the invention. It is therefore intended that the appended claims be interpreted as including all such changes and modifications.

What is claimed is:

1. In an electrostatic reproduction machine having heat transfer means for removing heat from a fusing assembly, apparatus for regulating the operation of said heat transfer means in accordance with a dimension of the sheets of material transported thereto, comprising:

switch means adapted to be activated for deenergizing said heat transfer means, said switch means being located at the supply of said sheets of material; and

activating means adapted to contact said switch means when said dimension of said sheets of material included in said supply exceeds a predetermined dimension, said switch means and said activating means being disposed for relative movement therebetween.

2. The apparatus of claim 1 wherein one of said switch means and said activating means is fixedly positioned and the other is mechanically coupled to sheet guide means and movable therewith when said sheet guide means is adjusted to receive sheets of material.

3. The apparatus of claim 2 wherein said sheet guide means comprises first and second movable members admitting of a separation therebetween substantially equal to said dimension of said sheets of material received thereby, said first and second movable members being disposed for movement. in opposite directions to provide an adjustment in said separation therebetween.

4. The apparatus of claim 3 wherein said switch means is fixedly positioned and includes a protruding member interposed in the path of travel of said activating means.

5. The apparatus of claim 4 wherein said activating bers are enabled to receive sheets of material supplied thereto, the path of travel of said rigid member being intersected by said protruding member such that said protruding member'is contacted by said rigid member when said first movable member is displaced to a predetermined position. 

1. In an electrostatic reproduction machine having heat transfer means for removing heat from a fusing assembly, apparatus for regulating the operation of said heat transfer means in accordance with a dimension of the sheets of material transported thereto, comprising: switch means adapted to be activated for de-energizing said heaT transfer means, said switch means being located at the supply of said sheets of material; and activating means adapted to contact said switch means when said dimension of said sheets of material included in said supply exceeds a predetermined dimension, said switch means and said activating means being disposed for relative movement therebetween.
 2. The apparatus of claim 1 wherein one of said switch means and said activating means is fixedly positioned and the other is mechanically coupled to sheet guide means and movable therewith when said sheet guide means is adjusted to receive sheets of material.
 3. The apparatus of claim 2 wherein said sheet guide means comprises first and second movable members admitting of a separation therebetween substantially equal to said dimension of said sheets of material received thereby, said first and second movable members being disposed for movement in opposite directions to provide an adjustment in said separation therebetween.
 4. The apparatus of claim 3 wherein said switch means is fixedly positioned and includes a protruding member interposed in the path of travel of said activating means.
 5. The apparatus of claim 4 wherein said activating means comprises a rigid member supported on drive means; said drive means being mechanically coupled to and movable with said first movable member and responsive to a motive force exerted thereon to drive said first movable member in a direction corresponding to the direction of said motive force to thereby adjust the separation between said first and second movable members whereby said first and second movable members are enabled to receive sheets of material supplied thereto, the path of travel of said rigid member being intersected by said protruding member such that said protruding member is contacted by said rigid member when said first movable member is displaced to a predetermined position. 